Currently, in most test strips for immunochromatography rapid detection, colloidal gold or a fluorescent pigment is used as a marker. In recent years, a breakthrough has been made in technologies in the immunofluorescence detection field. A time-resolved fluorescence (Time-resolved fluorescence, TRF) immunochromatography technology is developed. This technology has features such as high sensitivity, strong specificity, long fluorescent lifetime, good stability, and no radioactive contamination, and can be widely applied in field quantitative detection, and is an important future development trend for an instant detection technology.
A specific operation process of the time-resolved fluorescence immunochromatography technology is: performing fluorescent pigment dyeing on a testing line (T) and a quality control line (C) on a test strip; placing the test strip into a detection sample, and when the detection sample contains a detection target that can be combined with the fluorescent pigment, performing fluorescent pigment dyeing on a measurement target of the sample; and then, stimulating, by irradiating the sample using stimulating light, the fluorescent pigment to emit fluorescence, and analyzing a final fluorescence intensity value to obtain type, concentration, and other information about the measurement target. This technology requires performing correct analysis on the measurement target according to fluorescence information in a short period of time.
However, in the process of stimulating fluorescence by irradiating the sample using stimulating light, in addition to the fluorescence emitted from the measurement target, that is, fluorescence about which information of a fluorescent pigment is marked on the sample, there are further two categories of interference fluorescence, where the interference fluorescence includes ambient background fluorescence and impurity-stimulated fluorescence. The so-called ambient background fluorescence includes auto-fluorescence of base solution of the sample or the test strip itself, reflected fluorescence that has a relatively wide waveband, leaked light of a detection system and electromagnetic interference, and so on; and the impurity-stimulated fluorescence is mainly a matter that includes a non-measurement target and is in the sample, where this type of matter may also be stimulated by stimulating light to emit fluorescence, only that a process of stimulating and quenching this type of fluorescence is different from a process of stimulating and quenching the measurement target. When a waveband of the foregoing interference fluorescence overlaps a waveband of fluorescence emitted by the fluorescent pigment, if intensity of fluorescence emitted by the interference fluorescence is extremely weak as compared with intensity of fluorescence emitted by the fluorescent pigment, concentration information about the target can be measured by using a traditional time-resolved fluorescence detection method. However, when the fluorescence emitted by the fluorescent pigment is not intense enough, a result of measurement analysis will be badly affected.
In the traditional time-resolved fluorescence detection method, in a process in which fluorescence emission stimulated by the stimulating light by irradiating the sample decays, detection is not performed on the fluorescence when the fluorescence emission is at a maximum value, but the fluorescence detection is delayed for a period of about 200 μs to wait for the impurity-stimulated fluorescence to quench and then starts. In this way, an impact of the foregoing second type of interference fluorescence is canceled and intensity of the fluorescence emitted by the dyed fluorescent pigment is obtained, and relatively accurate information about the measurement target is acquired. In this method, although an impact of that an interfering substance stimulates fluorescence can be canceled, because of an uncertainty of the interfering substance, control over the delay of fluorescence detection is also uncertain. Therefore, it cannot be ensured that fluorescence stimulated by all interfering substances is completely canceled, and the foregoing method cannot be used to cancel interference of the first type of interference fluorescence, the ambient bias light, such as background auto-fluorescence, leaked light of a detection system, or electromagnetic interference.